Classification: Central nervous system (CNS) depressant

Background: Medetomidine is a potent surgical anesthetic approved for veterinary use in both large and small animals. Another form of the drug, dexmedetomidine is utilized in human medicine in hospital for sedation and as a sublingual film for the treatment of agitation associated with schizophrenia or bipolar I or II disorder in adults. Clinically, it is used to induce sedation, analgesia, anxiolysis, and muscle relaxation in both humans and animals. The compound belongs to the class of a2-adrenoceptor agonists, which also includes xylazine, romifidine, and detomidine. Veterinary studies have shown medetomidine to be a more potent, selective, and specific agonist in the peripheral and central nervous systems than xylazine.

Medetomidine is the latest CNS depressant to appear as an adulterant alongside fentanyl in the recreational drug supply. Medetomidine began appearing regularly in the Maryland drug supply following its first detection in July 2022. In 2024, it began appearing in Philadelphia and Pittsburg, Pennsylvania, and most recently in Chicago, Illinois.

In cases where medetomidine ingestion is suspected or confirmed, severe adverse effects have been noted, including heightened sedation and profound bradycardia. The Center for Forensic Science Research and Education issued a Toxic Adulterant Alert in December 2023 following its emergence in the recreational drug supply and in May 2024 following a large scale outbreak of overdoses and adverse events in Chicago.

Prescribed as: Dexmedetomidine is available as Precedex® injection solution and Igalmi® sublingual film for human use. Differing forms of medetomidine are available for use in veterinary medicine.

Street Names: Tranq

Modes of Use: Smoked, intravenous, intranasal and oral.

Physiological / Psychological Effects: The effects of medetomidine can include sedation, analgesia, muscle relaxation, anxiolysis, bradycardia, hypotension, hyperglycemia, and hallucinations. Duration of action is noted to be longer for medetomidine relative to xylazine.

Toxicity: Sedation, analgesia, dry mouth, respiratory depression, hypnotic/anesthetic effects, mydriasis, hypothermia, spontaneous muscle contractions (twitching), bradycardia, initial hypertension, followed by prolonged hypotension.

Atipamezole (Antisedan®) is widely used in veterinary medicine to reverse dexmedetomidine effects but not in humans due to unwanted symptoms, such as emesis, motor restlessness, and an increase in blood pressure.

Medetomidine does not respond to the opioid antagonist naloxone (Narcan®). However, naloxone administration is recommended in illicit drug exposure because medetomidine is almost always found in combination with opioids.

Metabolism: Detected unchanged in urine along with methylated and oxidative metabolites.    

Detection Time in Urine: 1–9 days